Q.1 What is the definition of capacitance?
The amount of charge a capacitor can store per unit voltage
The amount of energy stored in a capacitor
The resistance of a capacitor
The current flowing through a capacitor
Explanation - Capacitance (C) is defined as the ratio of the charge (Q) on the plates of a capacitor to the voltage (V) across it: C = Q / V.
Correct answer is: The amount of charge a capacitor can store per unit voltage
Q.2 If a capacitor stores 8 coulombs of charge when 4 volts are applied, what is its capacitance?
2 Farads
0.5 Farads
16 Farads
32 Farads
Explanation - C = Q / V = 8 C / 4 V = 2 F.
Correct answer is: 2 Farads
Q.3 Increasing the area of the plates of a parallel‑plate capacitor while keeping separation constant does what to the capacitance?
Increase it
Decrease it
Keep it the same
Make it zero
Explanation - Capacitance for a parallel‑plate capacitor is C = εA/d; larger area A increases C.
Correct answer is: Increase it
Q.4 If the separation between the plates of a capacitor is doubled, the capacitance will:
Double
Halve
Remain the same
Become zero
Explanation - C = εA/d; doubling d halves C.
Correct answer is: Halve
Q.5 What happens to the electric field inside a parallel‑plate capacitor when a dielectric with εr = 2 is inserted?
It doubles
It halves
It remains the same
It becomes zero
Explanation - The dielectric reduces the electric field by a factor of εr: E_new = E / εr.
Correct answer is: It halves
Q.6 What is the energy stored in a capacitor when its capacitance is 5 µF and the voltage across it is 12 V?
0.36 J
0.72 J
1.08 J
2.16 J
Explanation - U = ½ C V² = 0.5 × 5×10⁻⁶ F × 12² V² ≈ 0.36 J.
Correct answer is: 0.36 J
Q.7 When two capacitors of 4 µF and 6 µF are connected in series, what is the equivalent capacitance?
10 µF
1.5 µF
2.4 µF
20 µF
Explanation - 1/Ceq = 1/4 + 1/6 → Ceq = 1.5 µF.
Correct answer is: 1.5 µF
Q.8 If two identical capacitors are connected in parallel, the equivalent capacitance:
Remains the same
Doubles
Halves
Increases by a factor of 4
Explanation - Ceq = C + C = 2C for identical capacitors in parallel.
Correct answer is: Doubles
Q.9 Which of these materials can be used as a dielectric in a capacitor?
Air
Copper
Water
Iron
Explanation - Air is an insulating material that can act as a dielectric; copper and iron are conductors, and water is a poor dielectric due to its conductivity.
Correct answer is: Air
Q.10 The dielectric strength of a material is:
The maximum voltage it can withstand before breaking down
The amount of charge it can store
Its ability to conduct electricity
Its mass density
Explanation - Dielectric strength is the highest electric field a material can tolerate without electrical breakdown.
Correct answer is: The maximum voltage it can withstand before breaking down
Q.11 What is the effect of inserting a dielectric slab that fills only half the space between the plates of a capacitor?
Capacitance becomes twice its original value
Capacitance becomes half its original value
Capacitance increases but not exactly to double
Capacitance remains unchanged
Explanation - The effective capacitance lies between the values for full and no dielectric; it increases but is less than double.
Correct answer is: Capacitance increases but not exactly to double
Q.12 The formula for capacitance of a cylindrical capacitor with inner radius r₁ and outer radius r₂ is:
C = 2πϵ₀L / (r₂ - r₁)
C = 2πϵ₀L / ln(r₂ / r₁)
C = ϵ₀A / d
C = ϵ₀π(r₂² - r₁²) / L
Explanation - The cylindrical capacitor capacitance depends on the logarithm of the radius ratio.
Correct answer is: C = 2πϵ₀L / ln(r₂ / r₁)
Q.13 When a dielectric is added to a capacitor, the electric field between the plates:
Increases
Decreases
Remains the same
Becomes zero
Explanation - Dielectrics reduce the electric field for the same applied voltage.
Correct answer is: Decreases
Q.14 Which of the following is true for a capacitor in an RC charging circuit?
Voltage across capacitor decreases over time
Current through resistor is constant
Voltage across capacitor approaches the supply voltage
Capacitance decreases over time
Explanation - During charging, the capacitor voltage rises towards the supply voltage as the resistor current decreases.
Correct answer is: Voltage across capacitor approaches the supply voltage
Q.15 The capacitance of a parallel plate capacitor is directly proportional to:
Plate separation
Area of the plates
Voltage across it
Current through it
Explanation - C = εA/d shows proportionality to area A.
Correct answer is: Area of the plates
Q.16 What is the unit of capacitance?
Volt
Ampere
Farad
Watt
Explanation - Capacitance is measured in farads, one coulomb per volt.
Correct answer is: Farad
Q.17 If a capacitor's capacitance increases, the energy stored in it for a fixed voltage will:
Decrease
Increase
Stay the same
Become zero
Explanation - U = ½ CV², so increasing C increases U at constant V.
Correct answer is: Increase
Q.18 What does the relative permittivity (dielectric constant) of a material represent?
Its electrical conductivity
Its ability to resist magnetic fields
The factor by which it increases the capacitance compared to vacuum
Its mass density
Explanation - εr = ε / ε₀, showing how the material increases capacitance over vacuum.
Correct answer is: The factor by which it increases the capacitance compared to vacuum
Q.19 Which of the following changes will NOT affect the capacitance of a parallel plate capacitor?
Increasing the plate area
Increasing the distance between plates
Adding a dielectric with εr = 2
Changing the shape of the plates from rectangular to circular but keeping area the same
Explanation - Capacitance depends on area, separation, and dielectric; shape doesn't matter if area is unchanged.
Correct answer is: Changing the shape of the plates from rectangular to circular but keeping area the same
Q.20 When two capacitors of values 3 µF and 7 µF are connected in parallel, the equivalent capacitance is:
3 µF
7 µF
10 µF
1 µF
Explanation - Ceq = 3 µF + 7 µF = 10 µF.
Correct answer is: 10 µF
Q.21 A capacitor with a dielectric inserted has a lower electric field for the same voltage than a capacitor without dielectric. What is the consequence on the energy stored?
Energy stored decreases
Energy stored increases
Energy stored remains the same
Energy stored becomes zero
Explanation - The dielectric increases capacitance, so for the same voltage U = ½ C V² increases.
Correct answer is: Energy stored increases
Q.22 The capacitance of a coaxial cable is determined by:
The length of the cable only
The voltage applied
The radii of the inner and outer conductors and the dielectric
The material of the conductor
Explanation - C = 2πϵL / ln(b/a) for coaxial geometry.
Correct answer is: The radii of the inner and outer conductors and the dielectric
Q.23 In a capacitor bank, increasing the number of capacitors in parallel:
Reduces the total capacitance
Has no effect on total capacitance
Increases the total capacitance
Creates a series circuit
Explanation - Adding capacitors in parallel adds their capacitances.
Correct answer is: Increases the total capacitance
Q.24 The displacement current is defined as:
The current through a resistor
The change of electric flux over time
The magnetic field produced by a current
The voltage across a capacitor
Explanation - Displacement current I_d = ε₀ dΦ_E/dt, representing time‑varying electric fields.
Correct answer is: The change of electric flux over time
Q.25 What does the Q factor of a capacitor describe?
The amount of charge it can store
The ratio of energy stored to energy lost per cycle
The speed of charging
The resistance of the dielectric
Explanation - Q = (2πfU) / P_dissipated; higher Q means lower dielectric losses.
Correct answer is: The ratio of energy stored to energy lost per cycle
Q.26 Which type of dielectric is often used in high‑frequency applications due to low losses?
Paper
Teflon (PTFE)
Ceramic
Glass
Explanation - Teflon has a very low dielectric loss tangent, making it suitable for high‑frequency circuits.
Correct answer is: Teflon (PTFE)
Q.27 When a dielectric is added to a capacitor, the electric displacement D remains:
Constant across the dielectric
Zero
Proportional to the electric field
Inverse of the permittivity
Explanation - D = εE; within the dielectric D is continuous at interfaces.
Correct answer is: Constant across the dielectric
Q.28 If a capacitor has a capacitance of 2 µF, what is the charge stored on its plates when connected to a 12 V battery?
24 µC
16 µC
12 µC
2 µC
Explanation - Q = CV = 2×10⁻⁶ F × 12 V = 24×10⁻⁶ C = 24 µC.
Correct answer is: 24 µC
Q.29 Which of the following best describes a variable capacitor?
A capacitor that changes its capacitance with a change in separation between its plates
A capacitor that changes its capacitance with temperature
A capacitor that changes its capacitance when voltage changes
A capacitor that changes its capacitance with time
Explanation - Variable capacitors adjust the plate distance or overlap area to vary C.
Correct answer is: A capacitor that changes its capacitance with a change in separation between its plates
Q.30 For a parallel‑plate capacitor with dielectric constant εr = 4 and vacuum permittivity ε₀ = 8.85×10⁻¹² F/m, what is the capacitance per unit area (C/A)?
3.54×10⁻¹¹ F/m²
8.85×10⁻¹¹ F/m²
1.77×10⁻¹¹ F/m²
3.54×10⁻¹² F/m²
Explanation - C/A = ε₀εr = 8.85×10⁻¹² × 4 = 3.54×10⁻¹¹ F/m².
Correct answer is: 3.54×10⁻¹¹ F/m²
Q.31 What is the capacitance of a spherical capacitor with inner radius a = 1 cm and outer radius b = 2 cm, filled with vacuum?
7.08×10⁻¹² F
2.23×10⁻¹² F
1.11×10⁻¹¹ F
8.85×10⁻¹² F
Explanation - C = 4πϵ₀ ab/(b - a); plugging values gives 7.08×10⁻¹² F.
Correct answer is: 7.08×10⁻¹² F
Q.32 Which parameter in the RC time constant τ = R C affects the speed at which a capacitor charges?
Only R
Only C
Both R and C equally
Neither R nor C
Explanation - τ = RC; larger R or C increases the charging time.
Correct answer is: Both R and C equally
Q.33 A capacitor with a dielectric slab that fills only half of the plate area has a capacitance:
Half of the full dielectric value
Double the no‑dielectric value
Between the no‑dielectric and full‑dielectric values
Equal to the full dielectric value
Explanation - Effective capacitance is a weighted average based on area fractions.
Correct answer is: Between the no‑dielectric and full‑dielectric values
Q.34 Which of the following materials has the highest dielectric constant among common insulators?
Air
Glass
Ceramic
Wood
Explanation - Ceramic dielectrics can reach εr > 100, higher than air or glass.
Correct answer is: Ceramic
Q.35 In a capacitor bank, why are capacitors often connected in parallel?
To increase the total resistance
To decrease the total capacitance
To increase the total capacitance and reduce equivalent series resistance
To avoid voltage drops
Explanation - Parallel connection adds capacitance and provides lower series resistance.
Correct answer is: To increase the total capacitance and reduce equivalent series resistance
Q.36 What happens to the electric field inside a dielectric when the applied voltage across a capacitor is increased, keeping other parameters constant?
It increases proportionally
It decreases
It remains the same
It becomes zero
Explanation - E = V/d; increasing V increases E for fixed d and dielectric.
Correct answer is: It increases proportionally
Q.37 The capacitance of a capacitor is increased when:
The dielectric constant is decreased
The plate separation is increased
The dielectric constant is increased
The voltage is increased
Explanation - C ∝ εr; higher dielectric constant leads to higher capacitance.
Correct answer is: The dielectric constant is increased
Q.38 For a parallel‑plate capacitor with a dielectric slab inserted over a fraction of the plate area, the effective capacitance is:
A simple average of the two capacitances
The sum of the two capacitances
The harmonic mean of the two capacitances
The geometric mean of the two capacitances
Explanation - C_eff = (f A ε0εr + (1‑f) A ε0) / d, which is a weighted average by area fraction f.
Correct answer is: A simple average of the two capacitances
Q.39 What is the main purpose of adding a dielectric material to a capacitor in practical circuits?
To increase resistance
To increase capacitance and reduce leakage current
To increase voltage rating only
To reduce capacitance
Explanation - Dielectrics allow higher charge storage and prevent direct conduction between plates.
Correct answer is: To increase capacitance and reduce leakage current
Q.40 Which of the following best describes the relationship between stored energy and capacitance for a fixed voltage?
Energy ∝ 1/C
Energy ∝ C
Energy ∝ C²
Energy ∝ √C
Explanation - U = ½ C V²; for constant V, U scales linearly with C.
Correct answer is: Energy ∝ C
Q.41 The presence of a dielectric inside a capacitor:
Always reduces the capacitance
Always increases the capacitance
Can increase or decrease capacitance depending on dielectric constant
Has no effect on capacitance
Explanation - Dielectrics have εr > 1, so they increase C compared to vacuum.
Correct answer is: Always increases the capacitance
Q.42 Which factor is NOT directly involved in determining the capacitance of a parallel‑plate capacitor?
Plate area
Separation distance
Voltage applied
Dielectric constant
Explanation - Capacitance depends on geometry and material; voltage is not a factor.
Correct answer is: Voltage applied
Q.43 What does the term 'fringe field' refer to in the context of capacitors?
The magnetic field around the capacitor
The electric field at the edges of the plates
The field inside the dielectric only
The field in the surrounding air
Explanation - Fringe fields are the non‑uniform electric fields at the plate edges.
Correct answer is: The electric field at the edges of the plates
Q.44 Increasing the thickness of the dielectric layer in a capacitor:
Increases capacitance
Decreases capacitance
Does not change capacitance
Only affects leakage current
Explanation - Increasing d in C = εA/d reduces C.
Correct answer is: Decreases capacitance
Q.45 The dielectric constant of water at room temperature is approximately 80. This means that:
Water conducts electricity well
Capacitance increases by 80 times compared to vacuum
Water has 80 times more mass density
It has 80 times higher resistance
Explanation - εr = 80 → C with water = 80 × C_vacuum.
Correct answer is: Capacitance increases by 80 times compared to vacuum
Q.46 For a parallel‑plate capacitor with plates of area 200 cm² and separation 0.5 mm, the capacitance in a vacuum is:
7.08 pF
2.23 pF
1.11 pF
0.35 pF
Explanation - C = ε0 A / d = 8.85×10⁻¹² × 0.02 / 5×10⁻⁴ ≈ 7.08×10⁻¹² F = 7.08 pF.
Correct answer is: 7.08 pF
Q.47 The energy density stored in a capacitor is highest when:
Capacitance is low
Capacitance is high
Voltage is low
Dielectric is air
Explanation - Energy density u = ½ εE²; higher capacitance at same voltage stores more energy.
Correct answer is: Capacitance is high
Q.48 What is the purpose of the dielectric in a transformer’s primary and secondary windings?
To store charge and reduce leakage inductance
To increase magnetic field
To increase electrical resistance
To act as a conductor between windings
Explanation - The dielectric in the core insulates windings and affects capacitance between them.
Correct answer is: To store charge and reduce leakage inductance
Q.49 When a capacitor is fully charged, the voltage across its plates:
Is zero
Is equal to the source voltage
Is twice the source voltage
Is half the source voltage
Explanation - A fully charged capacitor blocks DC, so its voltage equals the source.
Correct answer is: Is equal to the source voltage
Q.50 The capacitance of a parallel‑plate capacitor is inversely proportional to:
Plate area
Plate separation
Dielectric constant
Voltage
Explanation - C = εA/d; increasing d lowers C.
Correct answer is: Plate separation
Q.51 Which of the following statements about capacitors in an AC circuit is correct?
They act as resistors at all frequencies
Their impedance decreases as frequency increases
Their impedance increases as frequency increases
They block AC signals entirely
Explanation - Z = 1/(jωC); higher ω (frequency) reduces impedance.
Correct answer is: Their impedance decreases as frequency increases
Q.52 Adding a dielectric material with εr = 3 between the plates of a capacitor will:
Triple the capacitance
Increase the capacitance by a factor of 3
Double the capacitance
Not change the capacitance
Explanation - C_new = εr × C_old; with εr = 3, C triples.
Correct answer is: Increase the capacitance by a factor of 3
Q.53 A capacitor is used as a filter in an electronic circuit. Which property is most important for this application?
Its resistance
Its capacitance value
Its dielectric constant
Its temperature coefficient
Explanation - The cutoff frequency of an RC filter depends on C.
Correct answer is: Its capacitance value
Q.54 Which of the following materials has the lowest dielectric constant?
Air
Polystyrene
Ceramic
Glass
Explanation - Air has εr ≈ 1, the lowest among insulators.
Correct answer is: Air
Q.55 If a capacitor is connected to a battery and the battery is disconnected, will the capacitor discharge spontaneously?
Yes, due to leakage current
No, unless there is a path for charge to escape
Yes, because capacitors lose charge over time
No, because capacitors never discharge
Explanation - A capacitor holds charge only if connected to a path; otherwise it remains charged.
Correct answer is: No, unless there is a path for charge to escape
Q.56 When a capacitor is connected in series with a resistor, the time constant τ depends on:
Only the resistor value
Only the capacitor value
Both the resistor and capacitor values
Neither of them
Explanation - τ = R × C determines how fast the capacitor charges/discharges.
Correct answer is: Both the resistor and capacitor values
Q.57 Which of the following best defines a ‘dielectric constant’?
The electrical conductivity of a material
The ratio of the capacitance with the dielectric to that without
The resistance of a material
The mass per unit volume of a material
Explanation - εr = C_with / C_vacuum.
Correct answer is: The ratio of the capacitance with the dielectric to that without
Q.58 If a capacitor with a dielectric slab partially covering the plates is connected to a battery, the electric field inside the dielectric region is:
Zero
Same as in the air gap
Reduced compared to the air gap
Increased compared to the air gap
Explanation - The dielectric reduces the electric field: E_dielectric = E_air / εr.
Correct answer is: Reduced compared to the air gap
Q.59 A parallel‑plate capacitor is designed to have a capacitance of 10 µF with a separation of 1 mm. If the area of the plates is increased to 4× the original area, the new capacitance will be:
2.5 µF
5 µF
10 µF
40 µF
Explanation - Capacitance scales linearly with area: C_new = 4 × C_old = 40 µF.
Correct answer is: 40 µF
Q.60 The dielectric constant of a material is found to be temperature dependent. This property is known as:
Dielectric anisotropy
Dielectric dispersion
Temperature coefficient of permittivity
Dielectric breakdown
Explanation - It describes how ε changes with temperature.
Correct answer is: Temperature coefficient of permittivity
Q.61 Which of the following is NOT a typical application of capacitors?
Energy storage
Filtering signals
Sensing pressure
Heat generation
Explanation - Capacitors store energy; heat generation is not a primary application.
Correct answer is: Heat generation
Q.62 In a series connection of two capacitors, the total capacitance:
Increases
Remains the same
Decreases
Becomes zero
Explanation - Series connection yields C_total = (1/C1 + 1/C2)^-1 < C1, C2.
Correct answer is: Decreases
Q.63 The capacitance of a capacitor increases when:
Its separation is reduced
Its area is reduced
Its dielectric constant is decreased
Its voltage is increased
Explanation - C ∝ 1/d; reducing d increases C.
Correct answer is: Its separation is reduced
Q.64 When a capacitor is connected to a battery of 12 V and has a capacitance of 2 µF, the stored energy is:
0.144 J
0.072 J
0.288 J
0.036 J
Explanation - U = ½ C V² = 0.5 × 2×10⁻⁶ × 12² = 0.144 J.
Correct answer is: 0.144 J
Q.65 Which of the following describes the effect of a dielectric on the electric displacement field D?
D is unchanged across the dielectric
D increases linearly with εr
D decreases inversely with εr
D becomes zero inside the dielectric
Explanation - D = εE; while E changes, the displacement field D remains continuous across boundaries.
Correct answer is: D is unchanged across the dielectric
Q.66 The capacitance of a capacitor can be measured by:
Using a voltmeter only
Using an ammeter only
Using a capacitance meter or LCR meter
By visual inspection
Explanation - Dedicated instruments measure capacitance directly.
Correct answer is: Using a capacitance meter or LCR meter
Q.67 What is the significance of the ‘Q’ factor in capacitors?
It represents the charge stored
It indicates the quality of the dielectric with low losses
It is the same as capacitance
It is the resistance of the capacitor
Explanation - Q factor measures energy loss relative to stored energy.
Correct answer is: It indicates the quality of the dielectric with low losses
Q.68 Which of the following best describes a capacitor’s behavior in a DC circuit after it has been fully charged?
It continues to supply current indefinitely
It acts as an open circuit
It acts as a short circuit
It acts as a resistor
Explanation - A fully charged capacitor blocks further DC current flow.
Correct answer is: It acts as an open circuit
Q.69 In a capacitor bank, why might designers choose to use capacitors with low dielectric losses?
To reduce weight
To improve energy efficiency at high frequencies
To increase the voltage rating
To lower manufacturing cost
Explanation - Low dielectric losses mean less energy dissipated as heat.
Correct answer is: To improve energy efficiency at high frequencies
Q.70 Which of the following is a correct expression for the capacitance of a parallel‑plate capacitor in a dielectric medium?
C = ε₀ A / d
C = ε₀εr A / d
C = ε₀ A / εr d
C = ε₀ A d / εr
Explanation - The dielectric constant εr scales the permittivity.
Correct answer is: C = ε₀εr A / d
Q.71 The dielectric strength of a material is expressed in units of:
Volts per meter
Farads
Ohms
Amperes
Explanation - Dielectric strength is the maximum electric field (V/m) it can withstand.
Correct answer is: Volts per meter
Q.72 A capacitor with plates of area 1 m² and separation 1 mm has a capacitance of approximately:
8.85 µF
8.85 pF
8.85 nF
8.85 mF
Explanation - C = ε₀ A / d = 8.85×10⁻¹² × 1 / 0.001 = 8.85×10⁻⁶ F = 8.85 µF.
Correct answer is: 8.85 µF
Q.73 Which of the following best describes the effect of temperature on the capacitance of a ceramic capacitor?
Capacitance increases with temperature
Capacitance decreases with temperature
Capacitance remains unchanged
Capacitance fluctuates randomly
Explanation - Ceramic dielectrics typically have a negative temperature coefficient.
Correct answer is: Capacitance decreases with temperature
Q.74 When a dielectric is partially inserted into a capacitor, the total capacitance can be represented by:
The arithmetic mean of the two capacitances
The harmonic mean of the two capacitances
The geometric mean of the two capacitances
A weighted average based on the inserted fraction
Explanation - C_eff = f C_dielectric + (1-f) C_air.
Correct answer is: A weighted average based on the inserted fraction
Q.75 A capacitor is used to smooth the output of a power supply. This application primarily relies on:
Its high resistance
Its high capacitance
Its high inductance
Its high voltage rating
Explanation - A large capacitance provides a steady DC voltage by filtering out ripple.
Correct answer is: Its high capacitance
Q.76 Which of the following changes will increase the breakdown voltage of a dielectric?
Increasing dielectric thickness
Increasing dielectric constant
Increasing temperature
Increasing applied voltage
Explanation - Breakdown field strength is constant; larger thickness allows higher voltage before breakdown.
Correct answer is: Increasing dielectric thickness
Q.77 The term ‘capacitance per unit area’ refers to:
C divided by the area of the plates
Area divided by C
The area of the plates only
The product of C and area
Explanation - It is the capacitance density, expressed as C/A.
Correct answer is: C divided by the area of the plates
Q.78 When a capacitor is connected to a DC source and then disconnected, the stored charge remains:
Zero, because capacitors discharge instantly
Constant, until leakage currents reduce it
Doubling, due to residual voltage
Halving, due to charge redistribution
Explanation - Charge remains until a path for discharge exists.
Correct answer is: Constant, until leakage currents reduce it
Q.79 The energy stored in a capacitor is related to the square of:
Capacitance
Voltage
Plate separation
Dielectric constant
Explanation - U = ½ C V²; energy ∝ V².
Correct answer is: Voltage
Q.80 What is the main advantage of using a dielectric material inside a capacitor for high‑voltage applications?
It reduces leakage current
It increases capacitance without changing geometry
Both A and B
It increases the voltage rating
Explanation - Dielectrics reduce conduction and allow more charge storage for same geometry.
Correct answer is: Both A and B
Q.81 Which of the following is a characteristic of a capacitor’s dielectric material?
High electrical conductivity
Low dielectric constant
Low dielectric loss
High magnetic permeability
Explanation - Low loss is desired to minimize energy dissipation.
Correct answer is: Low dielectric loss
Q.82 In a parallel‑plate capacitor, if the dielectric constant is 10, the electric field inside the dielectric will be:
10 times greater than in vacuum
10 times smaller than in vacuum
Same as in vacuum
Zero
Explanation - E = V/d; with dielectric, E is reduced by factor εr.
Correct answer is: 10 times smaller than in vacuum
Q.83 When two capacitors are connected in parallel, the equivalent capacitance:
Is equal to the smaller of the two
Is equal to the larger of the two
Is the sum of the two capacitances
Is the product of the two capacitances
Explanation - Parallel addition: C_eq = C1 + C2.
Correct answer is: Is the sum of the two capacitances
Q.84 What effect does a dielectric have on the electric displacement field D in a capacitor?
It doubles D
It halves D
It keeps D constant
It makes D zero
Explanation - D = εE; across boundaries, D is continuous.
Correct answer is: It keeps D constant
Q.85 The capacitance of a spherical capacitor with inner radius a and outer radius b is given by:
C = 4πϵ₀ ab/(b - a)
C = 4πϵ₀ (b - a)/ab
C = 4πϵ₀ ab(b - a)
C = 4πϵ₀ (b + a)/ab
Explanation - Formula derived from integration of field between concentric spheres.
Correct answer is: C = 4πϵ₀ ab/(b - a)
Q.86 Which of the following best describes the voltage across a capacitor in an RC circuit as it charges?
Linear increase with time
Exponential approach to supply voltage
Instant jump to supply voltage
Zero at all times
Explanation - V(t) = V_source (1 - e^(-t/RC)).
Correct answer is: Exponential approach to supply voltage
Q.87 If a capacitor has a dielectric that occupies 75% of the space between the plates, its capacitance relative to vacuum is:
0.25 times
0.75 times
1.25 times
1.75 times
Explanation - Effective C = C_vacuum (1 - f + fεr); with f=0.75, εr=1 for air, it's 1.25×C_vacuum.
Correct answer is: 1.25 times
Q.88 A capacitor is used in a timing circuit. The time constant is primarily determined by:
Capacitance only
Resistor only
The product of capacitance and resistor
The sum of capacitance and resistor
Explanation - Time constant τ = R × C.
Correct answer is: The product of capacitance and resistor
Q.89 What does the term 'dielectric loss tangent' refer to?
The ratio of dielectric constant to resistivity
The tangent of the angle between D and E vectors
The ratio of energy lost to energy stored in a dielectric
The slope of the capacitance vs. temperature curve
Explanation - Loss tangent (tanδ) quantifies dielectric losses.
Correct answer is: The ratio of energy lost to energy stored in a dielectric
Q.90 A capacitor with a capacitance of 4 µF is connected to a 12 V battery. The charge stored on the plates is:
48 µC
48 C
32 µC
8 µC
Explanation - Q = CV = 4 µF × 12 V = 48 µC.
Correct answer is: 48 µC
Q.91 Which of the following is a common dielectric material used in electrolytic capacitors?
Silicon dioxide
Aluminium oxide
Nickel‑chrome
Lead sulfide
Explanation - Aluminium electrolytic capacitors use Al₂O₃ as dielectric.
Correct answer is: Aluminium oxide
Q.92 In a capacitor bank, the equivalent series resistance (ESR) is important because it:
Increases the total capacitance
Reduces energy loss due to heating
Is unrelated to performance
Only affects AC signals
Explanation - ESR causes power dissipation as heat.
Correct answer is: Reduces energy loss due to heating
Q.93 The displacement current in a capacitor is non‑zero even when:
The voltage is constant
The current is zero
The electric field is zero
The plates are disconnected
Explanation - A changing electric field (even with constant voltage over time) produces displacement current.
Correct answer is: The voltage is constant
Q.94 What is the unit of electric displacement field D?
C/m²
V/m
A/m
F/m
Explanation - D has units of charge per unit area.
Correct answer is: C/m²
Q.95 The capacitance of a capacitor is directly proportional to:
Plate area
Plate separation
Voltage across it
Frequency of operation
Explanation - C ∝ A.
Correct answer is: Plate area
Q.96 Which of the following best explains why capacitors are used in power factor correction?
They store energy during the peak current cycle and release it during the valley
They increase the total resistance of the circuit
They act as voltage multipliers
They eliminate the need for transformers
Explanation - Capacitors shift current phase relative to voltage to improve power factor.
Correct answer is: They store energy during the peak current cycle and release it during the valley
Q.97 When a dielectric slab is inserted into a capacitor partially, the equivalent capacitance is:
The average of the capacitances of the two regions
The maximum of the two capacitances
The minimum of the two capacitances
The product of the two capacitances
Explanation - Effective capacitance is a weighted average based on area fraction.
Correct answer is: The average of the capacitances of the two regions
Q.98 Which of the following is NOT a function of a capacitor in an electronic circuit?
Smoothing DC supply
Filtering noise
Acting as an inductor
Storing energy
Explanation - Capacitors and inductors perform opposite functions in AC circuits.
Correct answer is: Acting as an inductor
Q.99 A capacitor with a dielectric constant of 5 and a capacitance of 2 µF will have a new capacitance:
1 µF
10 µF
5 µF
20 µF
Explanation - C_new = εr × C_old = 5 × 2 µF = 10 µF.
Correct answer is: 10 µF
Q.100 The energy stored in a capacitor is maximum when the capacitance:
Is smallest
Is largest
Is zero
Is negative
Explanation - Energy U = ½ CV²; larger C gives more energy at fixed V.
Correct answer is: Is largest
Q.101 A dielectric with high dielectric constant but high loss tangent is undesirable because:
It dissipates a lot of power as heat
It does not increase capacitance
It blocks AC signals
It reduces the breakdown voltage
Explanation - High loss tangent means significant energy loss in the dielectric.
Correct answer is: It dissipates a lot of power as heat
Q.102 Which of the following best explains why capacitors are used in timing circuits?
They provide a predictable delay based on RC time constant
They increase the frequency of oscillation
They act as resistors in series
They act as voltage regulators
Explanation - RC circuits use capacitors to set timing intervals.
Correct answer is: They provide a predictable delay based on RC time constant
Q.103 The capacitance of a capacitor is inversely proportional to:
Plate area
Plate separation
Dielectric constant
Voltage
Explanation - C ∝ 1/d.
Correct answer is: Plate separation
Q.104 What is the main purpose of the dielectric in a capacitor?
To conduct electricity
To store electric field energy
To block magnetic fields
To act as a resistor
Explanation - Dielectrics allow storage of charge in the capacitor.
Correct answer is: To store electric field energy
Q.105 If two capacitors of 5 µF and 10 µF are connected in series, the equivalent capacitance is:
15 µF
1.67 µF
3.33 µF
5 µF
Explanation - C_eq = (1/5 + 1/10)^-1 = 1.67 µF.
Correct answer is: 1.67 µF
Q.106 What happens to the capacitance of a capacitor if the dielectric constant is increased while keeping other parameters constant?
It increases
It decreases
It remains unchanged
It becomes infinite
Explanation - C ∝ εr; higher εr leads to higher C.
Correct answer is: It increases
Q.107 The term 'dielectric breakdown' refers to:
The point at which a dielectric starts conducting
The maximum voltage a capacitor can block
The minimum voltage a capacitor can withstand
The resistance of the dielectric
Explanation - Dielectric breakdown occurs when the electric field exceeds the material's tolerance.
Correct answer is: The point at which a dielectric starts conducting
Q.108 Which of the following is a correct expression for the energy stored in a capacitor?
U = CV
U = ½ CV²
U = CV²
U = C²V
Explanation - Standard energy formula for a capacitor.
Correct answer is: U = ½ CV²
Q.109 A capacitor's capacitance is increased by:
Increasing plate area
Increasing plate separation
Removing the dielectric
Lowering the dielectric constant
Explanation - C ∝ A.
Correct answer is: Increasing plate area
Q.110 The electric field inside a capacitor without a dielectric is:
Zero
Uniform and directed from positive to negative plate
Varying randomly
Only at the edges
Explanation - In a parallel‑plate capacitor, E is uniform across the gap.
Correct answer is: Uniform and directed from positive to negative plate
Q.111 A capacitor with a dielectric inserted partially will have its capacitance:
Exactly the same as with full dielectric
Exactly half of the full dielectric value
Between the no‑dielectric and full‑dielectric values
Zero
Explanation - Effective capacitance depends on the fraction of space filled.
Correct answer is: Between the no‑dielectric and full‑dielectric values
Q.112 Which of the following statements about capacitors is false?
They store electric energy
They have no resistance
They can act as short circuits at high frequencies
They block DC once fully charged
Explanation - In reality, capacitors have ESR and leakage resistance.
Correct answer is: They have no resistance
Q.113 If a capacitor’s plate separation is reduced by half, the new capacitance will be:
Half of the original
Double the original
Four times the original
Same as the original
Explanation - C ∝ 1/d; halving d doubles C.
Correct answer is: Double the original
Q.114 What is the unit of capacitance per unit area (C/A)?
Farads per meter
Farads per square meter
Farads per meter squared
Farads per meter cubed
Explanation - C/A has units F/m².
Correct answer is: Farads per square meter
Q.115 A capacitor can be considered as a:
Resistor
Inductor
Energy storage device
Magnetic field generator
Explanation - Capacitors store electrical energy.
Correct answer is: Energy storage device
Q.116 Which of the following is the correct expression for the capacitance of a parallel plate capacitor with a dielectric?
C = ε₀ A / d
C = ε₀εᵣ A / d
C = ε₀ A d / εᵣ
C = ε₀ A / (εᵣ d)
Explanation - Dielectric increases permittivity by εᵣ.
Correct answer is: C = ε₀εᵣ A / d
Q.117 Which of these is a key parameter for determining the performance of a capacitor in a high‑frequency application?
Dielectric loss tangent
Dielectric constant
Capacitance value
All of the above
Explanation - All these factors influence AC behavior.
Correct answer is: All of the above
Q.118 Which of the following is the most likely effect of increasing the temperature of a ceramic capacitor?
Capacitance increases
Capacitance decreases
Capacitance remains unchanged
Capacitance becomes negative
Explanation - Ceramic dielectrics typically have a negative temperature coefficient.
Correct answer is: Capacitance decreases
Q.119 If a dielectric with εr = 3 is inserted into a capacitor of area 50 cm² and plate spacing 1 mm, the new capacitance will be:
3× the vacuum capacitance
1/3× the vacuum capacitance
Equal to the vacuum capacitance
Zero
Explanation - C_new = εr × C_vacuum.
Correct answer is: 3× the vacuum capacitance
Q.120 The electric field inside a capacitor is:
Zero everywhere
Non‑zero only in the dielectric
Uniform between the plates
Only at the edges
Explanation - Parallel‑plate capacitor yields uniform field.
Correct answer is: Uniform between the plates
Q.121 The capacitance of a cylindrical capacitor is proportional to the length of the capacitor and:
The difference of radii
The logarithm of the ratio of radii
The product of radii
The sum of radii
Explanation - C = 2πϵL / ln(b/a).
Correct answer is: The logarithm of the ratio of radii
Q.122 In an AC circuit, the impedance of a capacitor is:
Z = 1/(jωC)
Z = jωC
Z = R
Z = C
Explanation - Capacitive impedance decreases with increasing frequency.
Correct answer is: Z = 1/(jωC)
Q.123 The dielectric constant of air is approximately:
0
1
10
100
Explanation - εr of air ≈ 1.
Correct answer is: 1
Q.124 The capacitance of a parallel‑plate capacitor with a dielectric slab occupying half the gap is:
Equal to the capacitance without dielectric
Half the capacitance without dielectric
Three‑quarters the capacitance without dielectric
Double the capacitance without dielectric
Explanation - C_eff = (1/2)C_air + (1/2)εrC_air; with εr=1 gives 0.75C.
Correct answer is: Three‑quarters the capacitance without dielectric
Q.125 In a capacitor, the displacement current is related to:
Changing magnetic field only
Changing electric field only
Both changing electric and magnetic fields
No change in fields
Explanation - Displacement current is due to ∂E/∂t.
Correct answer is: Changing electric field only
Q.126 The energy stored in a capacitor is maximum when the:
Voltage is maximum
Capacitance is maximum
Both voltage and capacitance are maximum
Neither voltage nor capacitance affect it
Explanation - U = ½ C V²; both factors increase energy.
Correct answer is: Both voltage and capacitance are maximum
Q.127 A capacitor with a dielectric constant of 4 and a capacitance of 5 µF will have a new capacitance:
20 µF
12.5 µF
10 µF
5 µF
Explanation - C_new = εr × C_old = 4 × 5 µF = 20 µF.
Correct answer is: 20 µF
Q.128 When a capacitor is connected to a DC source, the current through the capacitor:
Is constant
Starts high and decays to zero
Starts at zero and rises
Is zero at all times
Explanation - Current flows during charging and decays exponentially.
Correct answer is: Starts high and decays to zero
Q.129 Which of the following best describes the effect of inserting a dielectric into a capacitor?
It increases the capacitance
It decreases the capacitance
It does not affect the capacitance
It reverses the polarity
Explanation - Dielectrics increase permittivity, thus C.
Correct answer is: It increases the capacitance
Q.130 The capacitance of a capacitor bank is determined by:
Only the largest capacitor
Only the smallest capacitor
The combination of all capacitors in series and parallel
The average capacitance of all capacitors
Explanation - Overall C depends on network configuration.
Correct answer is: The combination of all capacitors in series and parallel
Q.131 A capacitor with a dielectric of εr = 2 and a separation of 2 mm stores twice as much energy as an identical capacitor without a dielectric, if both are charged to the same voltage.
True
False
Only at high voltage
Only at low voltage
Explanation - Energy U ∝ C, and C doubled due to εr = 2.
Correct answer is: True
Q.132 The electric displacement D inside a dielectric is:
Always zero
Always equal to the applied electric field
Proportional to the permittivity times the electric field
Inversely proportional to the permittivity
Explanation - D = εE.
Correct answer is: Proportional to the permittivity times the electric field
Q.133 The capacitance of a parallel plate capacitor is directly proportional to:
The area of the plates
The plate separation
The dielectric constant
The voltage applied
Explanation - C ∝ A.
Correct answer is: The area of the plates
Q.134 In a capacitor bank, adding more capacitors in series:
Increases total capacitance
Decreases total capacitance
Has no effect on total capacitance
Creates a parallel connection
Explanation - Series connection reduces equivalent capacitance.
Correct answer is: Decreases total capacitance
Q.135 The capacitance of a capacitor is given by C = Q/V. If Q is doubled while V stays the same, C is:
Halved
Unchanged
Doubled
Quadrupled
Explanation - C = Q/V; doubling Q doubles C.
Correct answer is: Doubled
Q.136 Which of the following is a correct relationship between capacitance and electric field in a parallel plate capacitor?
C = ε₀E/A
C = A/(ε₀E)
C = ε₀A/E
C = ε₀A·E
Explanation - From C = ε₀A/d and E = V/d, combine to get C = ε₀A/E.
Correct answer is: C = ε₀A/E
Q.137 The capacitance of a parallel‑plate capacitor with a dielectric of thickness 0.5 mm and area 200 cm² is:
7.08 µF
1.77 µF
2.23 µF
0.35 µF
Explanation - C = ε₀ A / d = 8.85×10⁻¹² × 0.02 / 5×10⁻⁴ = 7.08×10⁻⁶ F.
Correct answer is: 7.08 µF
Q.138 The energy density in a capacitor is given by:
U/V
U/A
U/d
U/(A·d)
Explanation - Energy density = energy per unit volume = U/(Ad).
Correct answer is: U/(A·d)
Q.139 A capacitor’s dielectric constant changes with frequency. This phenomenon is known as:
Dielectric dispersion
Dielectric relaxation
Dielectric hysteresis
Dielectric anisotropy
Explanation - Dielectric dispersion describes frequency‑dependent ε.
Correct answer is: Dielectric dispersion
Q.140 The capacitance of a capacitor is inversely proportional to the:
Area of the plates
Plate separation
Dielectric constant
Voltage applied
Explanation - C ∝ 1/d.
Correct answer is: Plate separation
Q.141 Which of these is NOT a typical dielectric material for a capacitor?
Polypropylene
Teflon
Copper
Ceramic
Explanation - Copper is a conductor, not a dielectric.
Correct answer is: Copper
Q.142 If a dielectric with εr = 5 is inserted into a capacitor of area 10 cm² and spacing 1 mm, the capacitance will be:
5× the vacuum capacitance
1/5× the vacuum capacitance
Equal to the vacuum capacitance
Zero
Explanation - C_new = εr × C_vacuum.
Correct answer is: 5× the vacuum capacitance
Q.143 The capacitance of a parallel‑plate capacitor is directly proportional to:
Plate area
Plate separation
Dielectric constant
Voltage across the plates
Explanation - C = εA/d.
Correct answer is: Plate area
Q.144 The total energy stored in a capacitor bank is:
Sum of energies of individual capacitors
Product of energies of individual capacitors
Energy of the largest capacitor only
Energy of the smallest capacitor only
Explanation - Energy is additive for capacitors in a network.
Correct answer is: Sum of energies of individual capacitors
Q.145 A dielectric slab that occupies half the plate area of a capacitor has an effective capacitance:
0.5× the full dielectric capacitance
0.75× the full dielectric capacitance
1.5× the full dielectric capacitance
Equal to the full dielectric capacitance
Explanation - Effective C = 0.5C_air + 0.5C_dielectric; with εr=1, C=0.75C_no_diel.
Correct answer is: 0.75× the full dielectric capacitance
Q.146 The electric field inside a capacitor with a dielectric is:
Zero
Uniform and reduced compared to vacuum
Only at the edges
Only inside the dielectric
Explanation - Dielectric reduces field strength by εr.
Correct answer is: Uniform and reduced compared to vacuum
Q.147 A capacitor’s capacitance increases if:
The plate area increases
The plate separation increases
The dielectric constant decreases
The voltage increases
Explanation - C ∝ A.
Correct answer is: The plate area increases
Q.148 The capacitance of a capacitor is:
Measured in ohms
Measured in farads
Measured in volts
Measured in coulombs
Explanation - Capacitance is expressed in farads (F).
Correct answer is: Measured in farads
Q.149 If a capacitor is connected to a 12 V battery and has a capacitance of 4 µF, the charge stored is:
48 µC
48 C
12 µC
4 µC
Explanation - Q = CV = 4×10⁻⁶ × 12 = 48×10⁻⁶ C.
Correct answer is: 48 µC
Q.150 Which of the following is a property of a capacitor that makes it useful in smoothing power supplies?
High resistance
High capacitance
Low inductance
High voltage rating
Explanation - High capacitance filters ripple.
Correct answer is: High capacitance
Q.151 The displacement current in a capacitor is given by:
I_d = C dV/dt
I_d = V/C
I_d = C V
I_d = dC/dt
Explanation - Displacement current equals capacitive current.
Correct answer is: I_d = C dV/dt
Q.152 A capacitor with a dielectric constant of 10 and a capacitance of 2 µF will have a new capacitance:
20 µF
10 µF
5 µF
2 µF
Explanation - C_new = εr × C_old = 10 × 2 µF = 20 µF.
Correct answer is: 20 µF
Q.153 The capacitance of a capacitor is given by:
C = V/Q
C = Q/V
C = V·Q
C = Q²/V
Explanation - Definition of capacitance.
Correct answer is: C = Q/V
Q.154 When a capacitor is fully charged, the voltage across it is:
Zero
Equal to the applied voltage
Half of the applied voltage
Double the applied voltage
Explanation - Fully charged capacitor blocks further current, matching source voltage.
Correct answer is: Equal to the applied voltage
Q.155 The dielectric constant of a material is also known as:
Relative permittivity
Absolute permittivity
Relative conductivity
Absolute conductivity
Explanation - εr is the relative permittivity of a dielectric.
Correct answer is: Relative permittivity
Q.156 The energy stored in a capacitor is calculated as:
U = CV
U = ½ CV²
U = CV²
U = ½ Q²/C
Explanation - Standard energy formula.
Correct answer is: U = ½ CV²
Q.157 The capacitance of a capacitor bank connected in series is:
Greater than any single capacitor
Equal to the largest capacitor
Less than the smallest capacitor
The sum of all capacitors
Explanation - Series reduces equivalent capacitance.
Correct answer is: Less than the smallest capacitor
Q.158 If a capacitor with a dielectric of εr = 4 is connected to a 12 V battery, the electric field inside the dielectric is:
12 V/m
3 V/m
48 V/m
0 V/m
Explanation - E = V/d; with d = 1 mm, E = 12k V/m. Inside dielectric, E = E_air/εr = 12k/4 = 3k V/m.
Correct answer is: 3 V/m
Q.159 Which of the following statements about dielectric materials is correct?
They conduct electricity easily
They have high electrical resistance
They are good conductors
They have negative dielectric constant
Explanation - Dielectrics are insulators with high resistance.
Correct answer is: They have high electrical resistance
Q.160 A capacitor with a dielectric inserted partially will have a capacitance:
Exactly the same as full dielectric
Half the full dielectric value
Between the no‑dielectric and full‑dielectric values
Zero
Explanation - Effective capacitance is a weighted average.
Correct answer is: Between the no‑dielectric and full‑dielectric values
Q.161 The capacitance of a capacitor is:
Measured in ohms
Measured in volts
Measured in farads
Measured in amperes
Explanation - Capacitance is expressed in farads.
Correct answer is: Measured in farads
Q.162 Which of the following best describes how the capacitance of a capacitor changes with frequency?
It increases with frequency
It decreases with frequency
It remains constant
It oscillates
Explanation - Ideal capacitor capacitance is independent of frequency.
Correct answer is: It remains constant
Q.163 The capacitance of a cylindrical capacitor is proportional to:
The difference between radii
The product of radii
The logarithm of the ratio of radii
The sum of radii
Explanation - C = 2πϵL / ln(b/a).
Correct answer is: The logarithm of the ratio of radii
Q.164 What happens to the capacitance of a capacitor when the dielectric constant is increased?
It increases
It decreases
It remains the same
It becomes zero
Explanation - C ∝ εr.
Correct answer is: It increases
Q.165 The voltage across a capacitor in series with a resistor during charging:
Remains constant
Increases exponentially
Decreases linearly
Remains zero
Explanation - V_c(t) = V(1 - e^(-t/RC)).
Correct answer is: Increases exponentially
Q.166 In a parallel‑plate capacitor with a dielectric slab inserted partially, the effective capacitance:
Is the average of the two capacitances
Is the product of the two capacitances
Is the sum of the two capacitances
Is the difference of the two capacitances
Explanation - Effective capacitance is a weighted average.
Correct answer is: Is the average of the two capacitances
Q.167 The capacitance of a spherical capacitor with inner radius a and outer radius b is:
C = 4πϵ₀ ab/(b - a)
C = 4πϵ₀ (b - a)/ab
C = 4πϵ₀ ab(b - a)
C = 4πϵ₀ (b + a)/ab
Explanation - Standard formula for a spherical capacitor.
Correct answer is: C = 4πϵ₀ ab/(b - a)
Q.168 When a capacitor is connected to a battery, the current through it:
Is constant
Starts high and decays to zero
Is zero at all times
Starts at zero and rises
Explanation - Charging current decreases as capacitor charges.
Correct answer is: Starts high and decays to zero
Q.169 The energy stored in a capacitor is maximum when:
Capacitance is maximum
Voltage is maximum
Both capacitance and voltage are maximum
Neither is maximum
Explanation - Energy U = ½ CV², so both increase energy.
Correct answer is: Both capacitance and voltage are maximum
Q.170 The capacitance of a capacitor is directly proportional to:
Plate area
Plate separation
Dielectric constant
Voltage
Explanation - C = εA/d.
Correct answer is: Plate area
Q.171 A capacitor bank connected in parallel:
Increases total capacitance
Decreases total capacitance
Has no effect on total capacitance
Creates a series connection
Explanation - Parallel connection adds capacitance.
Correct answer is: Increases total capacitance
Q.172 If the dielectric constant of a material is 3, the capacitance of a capacitor with that dielectric is:
Three times that of the same capacitor without dielectric
One-third that of the same capacitor without dielectric
Same as without dielectric
Zero
Explanation - C_new = εr × C_old.
Correct answer is: Three times that of the same capacitor without dielectric
Q.173 The capacitance of a parallel‑plate capacitor is inversely proportional to:
Plate area
Plate separation
Dielectric constant
Voltage
Explanation - C ∝ 1/d.
Correct answer is: Plate separation
Q.174 Which of the following is the correct relationship between capacitance and charge in a capacitor?
C = V/Q
C = Q/V
C = V·Q
C = Q²/V
Explanation - Definition of capacitance.
Correct answer is: C = Q/V
Q.175 The dielectric constant of a material is:
The ratio of the capacitance with dielectric to that without
The absolute permittivity
The conductivity of the material
The resistance of the material
Explanation - Relative permittivity definition.
Correct answer is: The ratio of the capacitance with dielectric to that without
Q.176 The energy stored in a capacitor is:
U = CV
U = ½ CV²
U = CV²
U = ½ Q²/C
Explanation - Standard energy formula.
Correct answer is: U = ½ CV²
Q.177 The capacitance of a capacitor increases when:
Plate area is increased
Plate separation is increased
Dielectric constant is decreased
Voltage is increased
Explanation - C ∝ A.
Correct answer is: Plate area is increased
Q.178 The capacitance of a capacitor is measured in:
Ohms
Volts
Farads
Amperes
Explanation - Capacitance unit is farad.
Correct answer is: Farads
Q.179 Which of the following statements about capacitors is false?
They store electrical energy
They have high resistance
They can act as inductors at high frequencies
They block DC after charging
Explanation - Capacitors block DC; they oppose changes in voltage but are not inductors.
Correct answer is: They can act as inductors at high frequencies
Q.180 A dielectric inserted in a capacitor reduces:
Capacitance
Electric field
Charge
Voltage across the plates
Explanation - Dielectric reduces E for same V.
Correct answer is: Electric field
Q.181 If a capacitor of 5 µF is charged to 10 V, the stored energy is:
0.25 J
0.5 J
2.5 J
5 J
Explanation - U = ½ C V² = 0.5 × 5×10⁻⁶ × 10² ≈ 0.25 J.
Correct answer is: 0.25 J
Q.182 Which of the following is NOT a typical dielectric material?
Polypropylene
Teflon
Ceramic
Copper
Explanation - Copper is a conductor, not a dielectric.
Correct answer is: Copper
Q.183 The capacitance of a capacitor is:
Inversely proportional to plate area
Directly proportional to plate area
Inversely proportional to dielectric constant
Directly proportional to voltage
Explanation - C ∝ A.
Correct answer is: Directly proportional to plate area
Q.184 The voltage across a capacitor during the RC charging process follows an:
Linear
Exponential
Quadratic
Sinusoidal
Explanation - V(t) = V_source (1 - e^(-t/RC)).
Correct answer is: Exponential
Q.185 If a dielectric slab occupies 30% of the gap between the plates of a capacitor, the effective capacitance is:
0.3× the vacuum capacitance
0.7× the vacuum capacitance
1.3× the vacuum capacitance
1.7× the vacuum capacitance
Explanation - Effective C = (1 - f)C_air + fC_dielectric; with εr=1, C_eff = 0.7C_no_diel.
Correct answer is: 0.7× the vacuum capacitance
Q.186 The dielectric constant of a material is:
The absolute permittivity
The ratio of the capacitance with dielectric to that without
The electrical conductivity
The resistance of the material
Explanation - Relative permittivity definition.
Correct answer is: The ratio of the capacitance with dielectric to that without
Q.187 The capacitance of a capacitor is:
Measured in farads
Measured in volts
Measured in coulombs
Measured in ohms
Explanation - Capacitance is in farads.
Correct answer is: Measured in farads
Q.188 The energy stored in a capacitor is:
U = CV
U = ½ CV²
U = CV²
U = ½ Q²/C
Explanation - Standard energy formula for a capacitor.
Correct answer is: U = ½ CV²